CN111370629B - Preparation method of self-supporting functional interlayer of lithium-sulfur battery - Google Patents

Preparation method of self-supporting functional interlayer of lithium-sulfur battery Download PDF

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CN111370629B
CN111370629B CN202010122407.7A CN202010122407A CN111370629B CN 111370629 B CN111370629 B CN 111370629B CN 202010122407 A CN202010122407 A CN 202010122407A CN 111370629 B CN111370629 B CN 111370629B
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CN111370629A (en
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张永光
王加义
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Zhaoqing South China Normal University Optoelectronics Industry Research Institute
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    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
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    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
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    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
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Abstract

The invention belongs to the technical field of lithium-sulfur batteries, and particularly relates to a preparation method of a self-supporting functional interlayer of a lithium-sulfur battery. The functional interlayer is a ZIF8/Mxene composite material doped with polyacrylonitrile nano-fiber. The functional interlayer effectively solves the problem that the shuttle effect of polysulfide in the existing lithium-sulfur battery is obvious and the defect of unstable electrochemical performance.

Description

Preparation method of self-supporting functional interlayer of lithium-sulfur battery
Technical Field
The invention belongs to the technical field of lithium-sulfur batteries, and particularly relates to a preparation method of a self-supporting functional interlayer of a lithium-sulfur battery.
Background
With the rapid development of scientific technology and information industry, renewable energy and new energy are urgently needed in the world at present. The lithium ion battery has the advantages of high specific energy, environmental friendliness, no pollution, abundant resources, low price and the like, and becomes a choice for energy storage equipment such as mobile electronic products and electric vehicles. The sulfur is used as the positive electrode material of the lithium-sulfur battery, the theoretical capacity of the lithium-sulfur battery reaches 1675mAh/g, the theoretical energy density of the lithium-sulfur battery can reach 2600Wh/kg, and the lithium-sulfur battery is considered to be one of the secondary batteries with the most development prospect. However, elemental sulfur has poor conductivity, the conductivity of the intermediate product in the charging and discharging process is also poor, and polysulfide has the problems of shuttle effect and the like in the reaction process, so that the utilization rate of the anode material is always in a low level, and the practical application of the anode material is influenced. Therefore, how to improve the cycle life of the lithium sulfur battery, improve the utilization rate of the positive active material, improve the conductivity of the lithium sulfur battery, and solve the problems of polysulfide shuttling effect becomes important for the research of the lithium sulfur battery.
In the prior art, a functional interlayer can be used for directly solving the shuttle effect of the lithium-sulfur battery, most of the functional interlayers utilize a common diaphragm, and the designed substances are coated on the surface of the diaphragm and exist between a pole piece and a lithium piece, so that the effect of physically or chemically fixing polysulfide to avoid shuttle is achieved, the utilization rate of positive active substances is improved, and the overall performance of the lithium-sulfur battery is improved.
In addition to coating the functional material on the surface of the separator, it is also a feasible technical means to directly use the self-supporting separator material as the functional separator of the lithium-sulfur battery. Carbon material with self-supporting structure due to its excellent conductivity and high ratioSurface area and high amount of functional barrier applied to lithium sulfur batteries. At present, multi-walled carbon nanotube paper (MWCNT) is used as a lithium-sulfur battery interlayer, and a self-supporting MWCNT flexible carbon interlayer is obtained through simple dispersion and vacuum filtration. Further adopts electrostatic spinning technology to obtain PAN nano-fiber paper, and then the PAN nano-fiber paper is carbonized with CO 2 And activating to obtain the carbon nanofiber interlayer with rich pore channel structures and the PAN-Nafion nanofiber interlayer which are applied to the lithium-sulfur battery. However, although the simple carbon material has a high specific surface area and good electrical conductivity, lithium polysulfide can be adsorbed only by physical adsorption depending on the specific surface area, and thus the ability of fixing the polysulfide is limited, which becomes an important factor that causes the self-supporting carbon material not to be widely used.
Disclosure of Invention
The invention aims to provide a preparation method of a self-supporting functional interlayer of a lithium-sulfur battery, aiming at the existing defects, wherein the functional interlayer effectively solves the problem that the 'shuttle effect' of polysulfide in the existing lithium-sulfur battery is obvious and the defect of unstable electrochemical performance.
The technical scheme of the invention is as follows: a self-supporting lithium-sulfur battery functional interlayer is a ZIF8/Mxene composite material doped with polyacrylonitrile nano-fibers.
The preparation method of the self-supporting lithium-sulfur battery functional interlayer comprises the following steps of firstly preparing MXene; then growing a layer of ZnO particles on the Mxene surface layer, and converting the ZnO particles into ZIF8 crystals in a self-conversion mode to prepare a ZIF8/Mxene composite material; and finally, fixing the ZIF8/Mxene composite material in a grid of polyacrylonitrile through electrostatic spinning to form a self-supporting lithium-sulfur battery functional interlayer.
The preparation method of the self-supporting functional interlayer of the lithium-sulfur battery comprises the following steps:
(1) Preparing MXene: immersing the grinded MAX phase ceramic powder into HF solution, heating, stirring, centrifuging to obtain a product, washing and drying the obtained centrifugal product to obtain MXene powder;
(2) Preparing a ZIF8/Mxene composite material: firstly, weighing MXene powder obtained in the step (1) and uniformly paving the MXene powder at the bottom of a porcelain boat; preparing a zinc acetate-ethanol solution, dropwise coating the MXene powder with the zinc acetate-ethanol solution by using a dripping method until the powder is wet, then placing the MXene powder in a drying oven at 60 ℃ for drying, repeating the dripping-drying operation for 3-6 times, then placing the porcelain boat in a muffle furnace for heat treatment, and cooling the porcelain boat along with the furnace after the heat treatment is finished to obtain MXene coated with ZnO particles; finally, weighing MXene coated with ZnO particles, fully dissolving the MXene in a dimethyl imidazole methanol solution, uniformly stirring, heating in a water bath, and centrifuging to collect the MXene coated with the ZnO particles to obtain a ZIF8/Mxene composite material;
(3) Preparing a functional interlayer: firstly, weighing polyacrylonitrile and the ZIF8/Mxene composite material prepared in the step (2), placing the weighed materials in N, N-dimethylformamide, and stirring to obtain a uniform solution; and then the uniform solution is taken to be subjected to electrostatic spinning to prepare the ZIF8/Mxene composite material doped polyacrylonitrile nanofiber, so that the functional interlayer is obtained.
The mass fraction of the HF solution in the step (1) is 30-50%.
Heating to 50-90 ℃ in the step (1), wherein the stirring is magnetic stirring, and the stirring time is 12-24 hours; washing the obtained centrifugal product to be neutral by deionized water, and drying the centrifugal product in an oven at the temperature of between 60 and 80 ℃ for 12 to 24 hours.
In the step (1), the MAX phase ceramic powder is Ti 3 AlC 2 、Ti 2 AlC、Cr 2 At least one of AlC; MXene obtained is Ti 3 C 2 T x 、Ti 2 CT x 、Cr 2 CT x At least one of (1).
0.5-1 g of MXene powder in the step (2), and the concentration of the zinc acetate-ethanol solution is 0.05-0.5 mol/L; MXene coated with ZnO particles is 0.1 to 1g, and the concentration of the dimethyl imidazole in methanol is 0.1 to 1mol/L.
The muffle furnace heat treatment in the step (2) is specifically as follows: heating to 200-300 ℃, and preserving heat for 6-12 h; the water bath heating temperature is 50-80 ℃, and the water bath time is 2-5 h.
In the step (3), polyacrylonitrile is 1-2g, ZIF8/Mxene composite material is 1-2g, and N, N-dimethylformamide is 10-20 mL; stirring for 12-24 hours.
The electrostatic spinning in the step (3) has the voltage of 18-22 kV, the flow rate of 0.03-0.1 mm/min, the spinning distance of 18-23 cm and the environmental humidity of 20-50%.
The beneficial effects of the invention are as follows: the functional interlayer of the self-supporting lithium-sulfur battery is a ZIF8/Mxene composite material doped with polyacrylonitrile nano-fibers. The characteristics of a metal organic framework ZIF8 and a metal organic framework Mxene are fully considered by the functional interlayer, the specific surface area of the ZIF8 is large, lithium polysulfide generated in the charging and discharging process of the lithium-sulfur battery has an obvious adsorption effect, the two-dimensional sheet layered structure of MXene enables the ZIF8 to be arranged in order, accumulation is avoided, the MXene has good conductivity, the defect that the conductivity of the ZIF8 is insufficient is overcome, the two functions act together, and the overall electrochemical performance of the battery is improved. The ZIF8 and the intermediate are used as ZIF8 intermediates through ZnO, so that the ZIF8 uniformly grows on the surface of Mxene, the problem of poor electronic conductivity of the ZIF8 is solved through close contact between the ZIF8 and the Mxene while the ZIF8 is effectively prevented from being agglomerated, the adsorption of the ZIF8 to polysulfide is facilitated, the two intermediates act together, respective advantages are fully played, and the overall electrochemical performance of the battery is effectively improved.
According to the preparation method, a layer of ZnO particles grows on the surface layer of the Mxene, znO is converted into ZIF8 crystals in a self-conversion mode, so that the ZIF8/Mxene composite material is prepared, and then the ZIF8/Mxene composite material is fixed in a grid of polyacrylonitrile through electrostatic spinning and directly used as a functional interlayer of the lithium-sulfur battery. Through the spinning means, the interlayer has good flexibility, and meanwhile, the spinning can enable the ZIF8/Mxene to be distributed more uniformly, so that the accumulation of materials is avoided, and the chemical adsorption effect of the materials on polysulfide can be effectively exerted.
In the preparation method, the surface of Mxene/ZIF8 is fully exposed while the flexibility of the material is effectively improved by electrostatic spinning, so that the adsorption effect on polysulfide is further improved, and the volume expansion of an electrode in the circulation process can be effectively relieved. Mxene/ZIF8 and polyacrylonitrile are woven together through electrostatic spinning to form a functional interlayer to block diffusion of polysulfide, the prepared functional interlayer is of a self-supporting structure and is obviously different from a traditional diaphragm coating method, the preparation process of the functional interlayer is simplified, and meanwhile the problem that effective components coated by the traditional method are crushed and fall off from a diaphragm in the battery circulation process is solved.
In conclusion, compared with the traditional method of coating the active material on the diaphragm, the interlayer can effectively avoid the accumulation of the active material, can expose larger specific surface area and more reactive active sites, and also avoids the problem of falling off of the active material in the long-term circulation process. Compared with the conventional self-supporting carbon material interlayer, the two-dimensional conductive material Mxene is combined with the three-dimensional porous organic framework ZIF8, the adsorption effect of the interlayer on polysulfide is further enhanced through chemical adsorption in addition to physical adsorption, the cycle performance of the battery can be more effectively improved, and the capacity attenuation rate of the battery is effectively reduced.
Drawings
FIG. 1 is a graph of specific discharge capacity cycling for lithium sulfur batteries using the functional separator prepared in examples 1-3.
Detailed Description
The present invention will be described in detail below with reference to examples.
Example 1
The functional interlayer of the self-supporting lithium-sulfur battery is a ZIF8/Mxene composite material doped with polyacrylonitrile nano-fibers.
The preparation method of the self-supporting functional interlayer of the lithium-sulfur battery is characterized by comprising the following steps of:
(1) Preparing MXene: immersing the grinded MAX-phase ceramic powder into HF solution with the mass fraction of 40%, heating to 60 ℃, magnetically stirring for 18 hours, centrifuging to obtain a product, washing the obtained centrifugal product to be neutral by deionized water, and drying in a drying oven at 70 ℃ for 18 hours to obtain MXene powder; MAX phase ceramic powder is Ti 3 AlC 2 、Ti 2 AlC、Cr 2 At least one of AlC; MXene obtained is Ti 3 C 2 T x (T x Is a functional group such as-OH, -F), ti 2 CT x (T x Is a functional group such as-OH, -F), cr 2 CT x (T x Is a functional group such as-OH, -F, etc.).
(2) Preparing a ZIF8/Mxene composite material: firstly, weighing 0.8g of MXene powder obtained in the step (1) and uniformly spreading the MXene powder on the bottom of a porcelain boat; then preparing a zinc acetate-ethanol solution with the concentration of 0.2mol/L, dropwise coating the MXene powder with the zinc acetate-ethanol solution by using a dropping coating method until the powder is wet, then placing the powder in a 60 ℃ drying oven to be dried, repeating the operations of dropwise coating and drying for 3-6 times, then placing a ceramic boat in a muffle furnace to be heated to 300 ℃, preserving heat for 8 hours, and cooling along with the furnace to obtain the MXene coated with ZnO particles; finally, weighing 0.3g of MXene coated with ZnO particles, fully dissolving the MXene in a methanol solution of dimethyl imidazole with the concentration of 0.5mol/L, uniformly stirring, heating in a water bath for 4 hours at the temperature of 60 ℃, and centrifugally collecting to obtain a ZIF8/Mxene composite material;
(3) Preparing a functional interlayer: firstly, weighing 1.5g of polyacrylonitrile and 1.5g of the ZIF8/Mxene composite material prepared in the step (2), placing the materials in 15mLN, N-dimethylformamide, and stirring for 18 hours to obtain a uniform solution; and then preparing the ZIF8/Mxene composite material doped polyacrylonitrile nano-fiber by taking the uniform solution through electrostatic spinning, firstly sucking the spinning solution into an injector during spinning, installing a needle head with the model of 20, setting the voltage to be 18-22 kV during spinning, setting the flow rate to be 0.03-0.1 mm/min, setting the spinning distance to be 18-23 cm, and controlling the ambient humidity to be 20-50%. After spinning is finished, the electrostatic spinning product is torn off from the tinfoil and then directly used as a functional interlayer of the lithium-sulfur battery, and the functional interlayer is directly arranged between a lithium sheet and a diaphragm in the process of assembling the battery.
Example 2
The preparation method of the self-supporting functional interlayer of the lithium-sulfur battery is characterized by comprising the following steps of:
(1) Preparing MXene: immersing the grinded MAX-phase ceramic powder into HF solution with the mass fraction of 50%, heating to 90 ℃, magnetically stirring for 24 hours, centrifuging to obtain a product, washing the obtained centrifugal product to be neutral by deionized water, and drying in a drying oven at 80 ℃ for 24 hours to obtain MXene powder; the MAX phase ceramic powder is Ti 3 AlC 2 、Ti 2 AlC、Cr 2 At least one of AlC; MXene obtained is Ti 3 C 2 T x 、Ti 2 CT x 、Cr 2 CT x At least one of (1).
(2) Preparing a ZIF8/Mxene composite material: firstly, weighing 1g of MXene powder obtained in the step (1) and uniformly spreading the MXene powder on the bottom of a porcelain boat; then preparing a zinc acetate-ethanol solution with the concentration of 0.5mol/L, dropwise coating the MXene powder with the zinc acetate-ethanol solution by using a dripping coating method until the powder is wet, then placing the powder in a drying oven at 60 ℃ for drying, repeating the dripping coating-drying operation for 3-6 times, then placing the ceramic boat in a muffle furnace for heating to 200-300 ℃, preserving heat for 6-12 hours, and cooling along with the furnace to obtain the MXene coated with ZnO particles; finally weighing 1g of MXene coated with ZnO particles, fully dissolving the MXene in a methanol solution of 1mol/L dimethyl imidazole, uniformly stirring, heating in a water bath for 5 hours at 80 ℃, and centrifugally collecting to obtain a ZIF8/Mxene composite material;
(3) Preparing a functional interlayer: firstly, weighing 2g of polyacrylonitrile and 2g of the ZIF8/Mxene composite material prepared in the step (2), placing the materials in 20mLN and N-dimethylformamide, and stirring for 24 hours to obtain a uniform solution; and then preparing the ZIF8/Mxene composite material doped polyacrylonitrile nano-fiber by taking the uniform solution through electrostatic spinning, firstly sucking the spinning solution into an injector during spinning, installing a needle head with the model of 20, setting the voltage to be 18-22 kV during spinning, setting the flow rate to be 0.03-0.1 mm/min, setting the spinning distance to be 18-23 cm, and controlling the ambient humidity to be 20-50%. After spinning is finished, the electrostatic spinning product is torn off from the tinfoil and then directly used as a functional interlayer of the lithium-sulfur battery, and the functional interlayer is directly arranged between a lithium sheet and a diaphragm in the process of assembling the battery.
Example 3
The preparation method of the self-supporting functional interlayer of the lithium-sulfur battery is characterized by comprising the following steps of:
(1) Preparing MXene: immersing the grinded MAX phase ceramic powder into a HF solution with the mass fraction of 30%, heating to 50 ℃, magnetically stirring for 12 hours, centrifuging to obtain a product, washing the obtained centrifugal product to be neutral by using deionized water, and drying in an oven at 60 ℃ for 12 hours to obtain MXene powder; MAX phase ceramic powder is Ti 3 AlC 2 、Ti 2 AlC、Cr 2 At least one of AlCOne kind of the material is selected; MXene obtained is Ti 3 C 2 T x 、Ti 2 CT x 、Cr 2 CT x At least one of (1).
(2) Preparing a ZIF8/Mxene composite material: firstly, weighing 0.5g of MXene powder obtained in the step (1) and uniformly spreading the MXene powder on the bottom of a porcelain boat; then preparing a zinc acetate-ethanol solution with the concentration of 0.05mol/L, dropwise coating the MXene powder with the zinc acetate-ethanol solution by using a dropping coating method until the powder is wet, then placing the powder in a 60 ℃ drying oven to be dried, repeating the dropping coating-drying operation for 3-6 times, then placing a ceramic boat in a muffle furnace to be heated to 200 ℃, preserving heat for 6 hours, and cooling along with the furnace to obtain the MXene coated with ZnO particles; finally, weighing 0.1g of MXene coated with ZnO particles, fully dissolving the MXene in a methanol solution of dimethyl imidazole with the concentration of 0.1mol/L, uniformly stirring, heating in a water bath at 50 ℃ for 2 hours, and centrifugally collecting to obtain a ZIF8/Mxene composite material;
(3) Preparing a functional interlayer: firstly, weighing 1g of polyacrylonitrile and 1g of the ZIF8/Mxene composite material prepared in the step (2), placing the materials in 10mLN and N-dimethylformamide, and stirring for 12 hours to obtain a uniform solution; and then preparing the ZIF8/Mxene composite material doped polyacrylonitrile nano-fiber by taking the uniform solution through electrostatic spinning, firstly sucking the spinning solution into an injector during spinning, installing a needle head with the model of 20, setting the voltage to be 18-22 kV during spinning, setting the flow rate to be 0.03-0.1 mm/min, setting the spinning distance to be 18-23 cm, and controlling the ambient humidity to be 20-50%. After spinning is finished, the electrostatic spinning product is torn off from the tinfoil and then directly used as a functional interlayer of the lithium-sulfur battery, and the functional interlayer is directly arranged between a lithium sheet and a diaphragm in the process of assembling the battery.
Analysis in conjunction with fig. 1 yields: example 2 used a higher concentration zinc acetate-ethanol solution to achieve the effect of excess ZIF8, and example 3 used a lower concentration zinc acetate-ethanol solution to achieve the effect of less ZIF8 incorporation. As can be seen from the electrochemical data in fig. 1, both excess ZIF8 and insufficient ZIF8 complexed with Mxene, the electrochemical performance of the resulting separator for lithium sulfur batteries was inferior to that of example 1 in terms of initial specific capacity as well as cycling performance. The interlayer plays a main functional role in Mxene and ZIF8, proper parameters are adopted, the control of the composite proportion of the Mxene/ZIF8 is of great importance, and the number of ZnO particles on the Mxene is the factor influencing the composite proportion. If the ZnO particles growing on the surface of Mxene are fewer, the phenomenon of uneven distribution is inevitably caused when the ZnO particles are converted into ZIF8, and the reduction of the quantity of the ZIF8 directly influences the catalytic performance of the material on polysulfide. If ZnO starts to grow in a large number of particles and grows very densely, incomplete conversion can occur firstly when the ZnO is converted into ZIF8, so that the ZIF8 and the Mxene are not tightly connected and are easy to fall off in a circulation process. Secondly, even if the ZIF8 is completely converted, the cross-linking phenomenon among ZIF8 particles can be caused, the surface of Mxene can be completely covered, so that electrons are difficult to penetrate through the ZIF8 to conduct on the Mxene, the conductive effect of the Mxene cannot be exerted, and the adsorption conversion effect of the material on polysulfide can be influenced to a certain degree. Therefore, the optimum effect of polysulfide adsorption can be achieved by selecting proper process condition parameters and reagent dosage to achieve the effect of uniform distribution of ZF8 particles on Mxene, and the method has a crucial effect on electrochemical performance. The invention obtains an optimal process parameter and reagent dosage range through creative labor.

Claims (7)

1. A self-supporting lithium-sulfur battery functional interlayer is characterized in that the functional interlayer is a ZIF8/Mxene composite material doped with polyacrylonitrile nano-fiber;
the functional interlayer is prepared by the following steps: firstly, MXene is prepared; then growing a layer of ZnO particles on the surface layer of the Mxene, and converting the ZnO particles into ZIF8 crystals in a self-conversion mode to prepare a ZIF8/Mxene composite material; finally, fixing the ZIF8/Mxene composite material in a grid of polyacrylonitrile through electrostatic spinning to form a self-supporting lithium-sulfur battery functional interlayer;
the method comprises the following specific steps:
(1) Preparing MXene: immersing the grinded MAX phase ceramic powder into HF solution, heating, stirring, centrifuging to obtain a product, washing and drying the obtained centrifugal product to obtain MXene powder;
(2) Preparing a ZIF8/Mxene composite material: firstly, weighing MXene powder obtained in the step (1) and uniformly spreading the MXene powder at the bottom of a porcelain boat; preparing a zinc acetate-ethanol solution, dropwise coating the MXene powder with the zinc acetate-ethanol solution by using a dripping method until the powder is wet, then placing the MXene powder in a drying oven at 60 ℃ for drying, repeating the dripping-drying operation for 3-6 times, then placing the porcelain boat in a muffle furnace for heat treatment, and cooling the porcelain boat along with the furnace after the heat treatment is finished to obtain MXene coated with ZnO particles; finally, weighing MXene coated with ZnO particles, fully dissolving the MXene in a methanol solution of dimethyl imidazole, uniformly stirring, heating in a water bath, and then centrifuging and collecting to obtain the ZIF8/Mxene composite material;
(3) Preparing a functional interlayer: firstly, weighing polyacrylonitrile and the ZIF8/Mxene composite material prepared in the step (2), placing the weighed materials in N, N-dimethylformamide, and stirring to obtain a uniform solution; then, preparing a ZIF8/Mxene composite material doped polyacrylonitrile nano fiber by taking the uniform solution through electrostatic spinning to obtain a functional interlayer;
wherein the muffle furnace heat treatment in the step (2) specifically comprises the following steps: heating to 200-300 ℃, and preserving heat for 6-12 h; the water bath heating temperature is 50-80 ℃, and the water bath time is 2-5 h.
2. The self-supporting lithium sulfur battery functional separator according to claim 1, wherein the mass fraction of the HF solution in step (1) is 30% to 50%.
3. The self-supporting lithium-sulfur battery functional barrier of claim 1, wherein in step (1), the temperature is raised to 50 to 90 ℃ by heating, and the stirring is magnetic stirring for 12 to 24 hours; washing the obtained centrifugal product to be neutral by deionized water, and drying the centrifugal product in an oven at the temperature of between 60 and 80 ℃ for 12 to 24 hours.
4. The self-supporting lithium sulfur battery functional separator according to claim 1 wherein the MAX phase ceramic powder in step (1) is at least one of Ti3AlC2, ti2AlC, cr2 AlC; the MXene is at least one of Ti3C2Tx, ti2CTx and Cr2 CTx.
5. The self-supporting lithium-sulfur battery functional barrier of claim 1, wherein in step (2), MXene powder is 0.5-1 g, and the concentration of the zinc acetate-ethanol solution is 0.05-0.5 mol/L; MXene coated with ZnO particles is 0.1 to 1g, and the concentration of the dimethyl imidazole in methanol is 0.1 to 1mol/L.
6. The self-supporting functional interlayer for lithium-sulfur batteries according to claim 1, wherein in the step (3), polyacrylonitrile is 1 to 2g, ZIF8/Mxene composite material is 1 to 2g, and N, N-dimethylformamide is 10 to 20mL; stirring for 12-24 hours.
7. The self-supporting lithium-sulfur battery functional separator according to claim 1, wherein the voltage of the electrospinning in step (3) is 18-22 kV, the flow rate is 0.03-0.1 mm/min, the spinning distance is 18-23 cm, and the ambient humidity is controlled to be 20-50%.
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